Abstract Proteins are frequently used as emulsifiers and stabilizers. In this work, two proteins with different isoelectric points were used: lactoferrin and ovalbumin. Solutions containing different proteins ratios, with different pH values, were stored for 7 days at 25 °C to analyze the system stability. Systems containing 3% w/v lactoferrin remained stable at all pH values studied, while systems containing 1% w/v ovalbumin remained stable only at a high pH value (8.0). Emulsions containing a mixture of proteins remained stable at a pH between the isoelectric points of the two proteins, which was attributed to an electrostatic bond because of the opposite charges of proteins at this pH. During the analysis of rheological properties, it was possible to observe a non-Newtonian behavior of the emulsions, using the models of Carreau and Cross to describe the pseudoplastic behavior of suspensions. This study provides important information for the use of functional ingredients.

Neste trabalho, a otimização do processo de formação de complexos interpoliméricos entre lactoalbumina e os polissacarídeos goma xantana e pectina foi estudada a fim de definir as condições ótimas para a formação dos complexos. Para o planejamento experimental foi utilizada a metodologia de superfície de resposta (MSR) para três variáveis independentes. As condições ótimas para a formação dos complexos entre lactoalbumina e goma xantana foi: pH 6,6, concentração de NaCl de 0,6 mol/L e concentração de goma xantana 0,083% m/v. E para os complexos formados entre lactoalbumina e pectina foram: pH 6,6, concentração de NaCl 0,25 mol/L e concentração de pectina, 0,113% m/v. O modelo matemático que melhor se ajustou aos dados experimentais foi o correspondente ao complexo goma xantana-lactalbumina, cujo coeficiente de determinação (R²) foi de 0,97.

In this work, the optimization process of interpolymeric complexes formation between lactalbumin and the polysaccharides xanthan gum and pectin was studied in order to define the optimum conditions for the complexes formation. For the experimental design, response surface methodology (RSM) for three independent variables was used. The optimum conditions for the complexes formation between lactalbumin and xanthan gum were: pH 6.6, NaCl concentration of 0.6 mol/L and xanthan gum concentration 0.083% w/v. And for the complexes formed between pectin and lactalbumin the conditions were: pH 6.6, NaCl concentration of 0.25 mol/L and pectin concentration of 0.113% w/v. The best fitted model for the experimental data was that corresponding to the complex xanthan gum-lactalbumin, whose coefficient of determination (R²) was 0.97.